1. Field of the Invention
The invention relates to a method and apparatus for distinguishing between flashes or other failure events that result from fiber breakdown and those arising from other sources, such as burning of tissues, during a laser surgical procedure.
2. Description of Related Art
U.S. patent application Ser. No. 61/006,077 (Publication Nos. 2009/0149845 and 2009/0177191) and U.S. patent application Ser. No. 11/714,785 (Publication No. 2007/0167937) describe optical feedback systems designed to prevent thermal runaway of a fiber tip when contaminated with biological tissues including blood by detecting damage radiation emitted during burning or overheating of the fiber tip. This thermal runaway can cause adverse effects such as pain, nerve damage, adjacent tissue damage, vein perforation and creation of toxic fumes. A commercial example of such a system if the LaserGuard™ system offered by Optical Integrity, Inc. of Panama City, Fla.
In some applications, such as removal of stones from the urinary tract, it may be difficult for the feedback system to distinguish between failure events caused by fiber breakdown, and failure events from other sources, such as heating of the stone. This can cause premature shutdown of the laser if the failure events are not the result of fiber breakdown, or damage resulting from a burning fiber tip if the failure events are ignored even though they are the result of fiber breakdown.